Manufacturing processes used in the preparation of pharmaceuticals, food, distillates and chemical compounds may include some type of sensor inspection of the mixing process, for example, spectral, pH, and thermal interrogation. These sensors are typically attached to a wall of a processing vessel, and monitor parameters of the process using a probe protruding into the manufacturing process. However, the stationary nature of sensors having a fixed position limits inspection capabilities to the product in the immediate vicinity of the sensor's fixed position and may not provide information about other parts of the process.
A collimating element may be required prior to variable optical filters to prevent the spectral selectivity of the linearly variable filter from being degraded. Degradation may happen because the optical filter may include a stack of thin dielectric films, and the wavelength-selective properties of thin film filters are generally dependent on the angle of incidence of incoming light, which may deteriorate spectral selectivity and wavelength accuracy of thin film filters. However, for the device in the present disclosure it may be beneficial to reduce the size of the spectrometer even more by eliminating bulky lenses.